高等有机化学-Lecture11资料.ppt

The Pinacol Rearrangement semi-pinacol rearrangement Tiffeneau-Demjanov Group moved as the following order: tertiary alkyl＞aryl＞H＞secondary alkyl ＞primary alkyl＞methyl The cumene hydroperoxide rearrangement is quite resemble the Baeyer-Villiger Rearrangement Important industrial reaction for manufacturing phenol and acetone Memory effects Longer Nucleophilic Rearrangement Free-Radical Rearrangements Electophilic Rearrangements 例 Favorskii Rearrangement Mechanism of Favorskii Rearrangement For asymmetric cycloprapanone, the stable anion form dominantly Different α- chloroketone form same rearrangement product: Intramolecular SN2 attack(structure maintaining): Stevens Rearrangement Structure maintaining The sulfonium cation does the same Sommelet Rearrangement Wittig Rearrangement Fries Rearrangement Reaction 1,2-rearrangements A. Carbon to carbon migrations of R, H, and Ar Wagner-Meerwein and related Reactions: t-BuCl t-BuCl * Advanced Organic Chemistry Lecture 11 Rearrangements Reactions Molecular Rearrangements: It refers those reactions in which the carbon skeleton or the position of functional group changed. 分子中的基团或原子从一个原子迁移到另一个原子上，碳胳或官能团的位置发生变化的一类反应称为分子重排反应。 Rearrangement was classified by the electron property of the moving group, such as Nucleophilic rearrangement, Electrophilic rearrangement, Radical rearrangement, etc. MECHANISMS Nucleophilic Rearrangements Whitmore 1,2-shift Open sextet Step I. Creation of a system with open sextet: Formation of a Carbocation Wagner-Meerwein rearrangement 2. Formation of a Nitrene Step II. Migration Step III. The migration origin (A) acquires an octet Rearrangement with substitution (combinations with a nucleophile) Rearrangement with elimination (loss of H+) The Actual Nature of the Migration The configeration of Y is retained Inversion of B Beckmann Rearrangement Racimation is found at B: Inversion occurs at B: SN1-like SN2-like When B is a teriary atom or has one aryl group and at least one other alk